Footage of great apes has revealed that humans aren’t the only ones enduring seemingly endless bouts of teasing dished out by their smaller and weaker cubs who seem bent on pushing their luck.
Surveys of chimpanzees, orangutans, bonobos and gorillas have found the animals to be masters of the dubious art, initiating an impressive range of playful and sometimes somewhat aggressive acts ranging from the cheeky and downright silly to the fabulously annoying.
From 75 hours of footage taken at San Diego and Leipzig zoos, scientists documented 142 clear cases of great apes teasing their friends, most of which were instigated by juveniles aged three to five.
The monkeys poked, bumped and ran away, offered objects and then withdrew them, body-slammed each other, stuck their faces in others’ faces, pulled on pieces of hair – a movement that is especially common in orangutans whose hair is generous enough – pulled on body parts, tickled and hung things in front of each other.
And that was just for the beginning. In total, the researchers in Germany and the US counted 18 different types of teasing in the footage. More than a fifth used an element of surprise, with a monkey approaching its target from behind or looking the other way.
“We can’t really say why they do it, but we can see that they do it,” said Dr Isabelle Laumer at the Max Planck Institute for Animal Behavior in Konstanz, Germany. “This playful teasing is provocative, intentional and typically one-sided. It comes a lot from the teaser and it often stays that way throughout the interaction.”
As with all the best teasing, a failure to respond to an unexpected jab, or a monkey’s face suddenly popping into view, was met with more of the same, with monkeys making their chosen move 84% of the time repeat or escalate the situation with more elaborate acts of annoyance.
The study of nine bonobos, four orangutans, four gorillas and 17 chimpanzees was too small to find major differences between the species, but adults and juveniles had different strategies. Touching was the most common form of teasing for both adults and juveniles, but while juveniles engaged in hitting and waving body parts at others, adults were gentler and preferred tickling and stealing.
“What’s interesting is that we found similarities with the teasing of human babies,” Laumer said. “When human babies tease their mother, they tend to look at their mother’s face for a response. We also see it with these great apes.”
Human infants engage in playful teasing as early as eight months and before they can produce words. Scientists believe the behavior can help test social boundaries and strengthen relationships.
Although most young monkeys targeted adults, they often spared their own parents, according to the study Proceedings of the Royal Society B. However, there were exceptions: Denny the gorilla repeatedly teased his parents, probably because there were few other gorillas around; and Aisha, the orangutan, has become adept at swinging a rope in her father’s face while he goes about his own business.
It will take more observation to understand why the animals might tease each other. But with the behavior seen in our closest primate cousins, teasing and the cognitive skills that underlie it can be traced back 13 million years to the last common ancestor that humans share with modern apes, Laumer said.
“Teasing has been discussed in relation to humour, but it can also contribute to the understanding of social partners,” says Dr Marina Davila-Ross, who studies the evolution of communication at the University of Portsmouth. “For example, if a young monkey teases another and the second one does not respond, this tells the first individual how far one can go with the second individual, and provides important information about growing up within a social group and the establishment of hierarchies.”
